From: Wanpeng Li <kernellwp@gmail.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Wanpeng Li" <wanpeng.li@hotmail.com>
Subject: [PATCH] x86/kvm: virt_xxx memory barriers instead of mandatory barriers
Date: Tue, 11 Apr 2017 02:49:21 -0700 [thread overview]
Message-ID: <1491904161-4099-1-git-send-email-wanpeng.li@hotmail.com> (raw)
From: Wanpeng Li <wanpeng.li@hotmail.com>
virt_xxx memory barriers are implemented trivially using the low-level
__smp_xxx macros, __smp_xxx is equal to a compiler barrier for strong
TSO memory model, however, mandatory barriers will unconditional add
memory barriers, this patch replaces the rmb() in kvm_steal_clock() by
virt_rmb().
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
arch/x86/kernel/kvm.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 14f65a5..da5c097 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -396,9 +396,9 @@ static u64 kvm_steal_clock(int cpu)
src = &per_cpu(steal_time, cpu);
do {
version = src->version;
- rmb();
+ virt_rmb();
steal = src->steal;
- rmb();
+ virt_rmb();
} while ((version & 1) || (version != src->version));
return steal;
--
2.7.4
next reply other threads:[~2017-04-11 9:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-11 9:49 Wanpeng Li [this message]
2017-04-11 14:20 ` [PATCH] x86/kvm: virt_xxx memory barriers instead of mandatory barriers Paolo Bonzini
2017-04-12 19:04 ` Radim Krčmář
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